Volume and Surface Area
Practice Questions - Volume and Surface Area
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Q11) If radius of a Hemisphere is decreased by 20%, find the percentage change in it's Curved Surface Area? 1) -36% 2) -20% 3) -40% 4) -44%
Curved Surface Area of a Hemisphere =2πr2 As, 2π is a constant hence, Curved Surface Area of a Hemisphere varies directly as the square of radius. So, Let us suppose the initial radius be 1 unit. Hence, Initial Curved Surface Area = 12 = 1 Radius of a Hemisphere is decreased by 20% ∴ New radius = 0.8 units Hence, Final Curved Sphere Area = (0.8)3 = 0.64  Hence, option 1. Q12) 25 stones of uniform size are thrown into a tank 50 m long, 40 m wide. If water displaced by a stone is 4 m3. Then what is the rise in water level (in cm) of the tank? 1) 0.05 cm 2) 50 cm 3) 5 cm 4) 10 cm
Rise in water level = h Total water displaced = 25×4 = 100 m3 100 = 50×40×h h = 0.05 m = 5 cm Hence, option 3. Q13) Length, breadth and height of a cuboid are decreased by 10%, 20% and 25% respectively. Find the percentage change in Volume. 1) -55% 2) -44% 3) -46% 4) -54%  Hence, option 3. Q14) A conical water tank of height 15 m and circumference of the base as 44 m is filled with water. How much water can be contained in this tank? 1) 770 cu m 2) 385 cu m 3) 1155 cu m 4) 660 cu m
Water contained in the conical tank = Volume of the cone Circumference of the base = 44 m  Hence, option 1. |